5.3.1: Practice Half-Life
- Page ID
- 424645
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Exercise \(\PageIndex{1}\)
How many years does it take for 4.7 half-lives to pass for a sample of sodium-22? The half-life of sodium-22 is 2.6 years..
- Answer
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12 years
Exercise \(\PageIndex{1}\)
How many half-lives have passed for a sample of gold-198 that is 3.4 weeks old? The half-life of gold-198 is 2.7 days.
- Answer
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8.8 half-lives
Exercise \(\PageIndex{1}\)
If you start with 422 mg of calcium-47, how much will remain after 5.00 half-lives have passed?
- Answer
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13.2 mg
Exercise \(\PageIndex{1}\)
The half-life of sodium-24 is 15.0 hours. If you begin with a sample that has 675 nCi of activity, what activity will remain after 3.75 days? (Hint: how many half-lives have passed for the sample after 3.75 days?)
- Hint
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6.00 half-lives have passed.
- Answer
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10.5 nCi of activity remain